Anatomy of the Circle of Willis
Overview
- The Circle of Willis is supplied by two main feeder pathways:
- Internal Carotid Artery: Supplies the anterior part.
- Vertebral Artery: Supplies the posterior part.
- The diagram discusses the structure from an inferior view.
- Right & Left Cerebral Hemispheres
- Right & Left Cerebellum
Vertebral Arteries Pathway
- Originate from the subclavian arteries.
- Travel through the transverse foramina of the cervical vertebrae.
- Proceed up through the foramen magnum.
- Branches:
- Posterior Inferior Cerebellar Artery (PICA)
- Posterior Spinal Arteries
Formation of Basilar Artery
- Vertebral arteries fuse together to form the basilar artery.
- Important branches from this merger:
- Anterior Spinal Artery: Supplies the spinal cord and medullary pyramids.
- Anterior Inferior Cerebellar Artery (AICA)
- Labyrinthine Arteries (also known as Internal Acoustic Arteries)
- Pontine Branches: Supply the pons.
- Superior Cerebellar Arteries: Supply the top of the cerebellum.
Basilar Artery Contribution to the Circle of Willis
- Feeds into the Posterior Cerebral Artery:
- Divided into p1 and p2 segments.
- Connects to the Posterior Communicating Arteries.
Internal Carotid Artery Pathway
- Supplies 80% of the Circle of Willis.
- Branches:
- Ophthalmic Artery
- Middle Cerebral Artery
- Anterior Choroidal Artery
- Lenticulostriate Arteries: Important for supplying the internal capsule and lentiform nucleus.
- Anterior Cerebral Artery
- Divided into a1 and a2 segments.
- Connects to the Anterior Communicating Artery.
Clinical Significance
- Occlusions or aneurysms in any of these arteries can lead to significant clinical conditions.
- Next topics to cover include cerebral ischemia and strokes.
Conclusion
- Essential to understand the anatomy of these vessels for diagnosing and understanding cerebral pathologies.
- Stay tuned for the next video on clinical implications.
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